A series whose coefficients satisfy three-term recurrence relations
like (REF ) truncates
on the right-hand side if \(\gamma _n=0\)  for some value of \(n\ge \) .
Precisely, if \(\gamma _{N+1}=0\) , the series becomes a finite series
with \(0\le n\le N\)  [1]}). So, we can write
\(\begin{array}{l}\gamma _{N+1}=0\quad \Rightarrow \quad \text{finite series with } n\le N.\end{array}\) 
